The present application claims priority to Japanese Application No. P2000-098902 filed Mar. 31, 2000, which application is incorporated herein by reference to the extent permitted by law.
The present invention relates to an optical recording medium having a writable recording layer having a maker recording area on an optical recording medium substrate, an optical recording method, an optical reproducing method, and an optical recording/reproducing device therefor.
In an optical medium such as an optical disk represented by, e.g., a mini disk (MD), for example, a so-called WO (Write Once) type optical recording medium on which data can be recorded once or a so-called RW (Rewritable) type optical recording medium on which data is rewritable, on a substrate molded by, e.g., an injection mold, in the molding, in a predetermined region of the substrate, a so-called premastered area in which information of a design center value of an illumination light power at, e.g., a standard temperature, i.e., a standard value, in optical recording or/and optical reproducing of the optical recording medium is written by pits or wobbled grooves is formed.
In this manner, in optical recording or/and optical reproducing of the optical recording medium, the information in the premastered area described above is loaded on a drive device for the optical recording medium, optical recording or/and optical reproducing is performed by using a value corrected by a set temperature as an optimum power. For this reason, a difference between the sensitivities of optical recording media of different makers is corrected.
However, in recent years, with a demand for a high recording density in an optical recording medium, margins (allowances) of characteristics required for the optical recording medium tend to be narrow. For this reason, in manufacturing an optical recording medium, it is required that the variation of characteristics caused by the manufacturing should be sufficiently close to a standard value given by the premastered.
As a concrete example of this variation, for example, recording power sensitivities will be exemplified. A variation of sensitivities of an outer peripheral portion and an inner peripheral portion of a disk-like optical recording medium in the radial direction, a variation of optical recording media in a manufacturing lot, and a variation of manufacturing lots are known. Of these variations, in sputtering in a film forming process of, e.g., a recording layer, a variation in a lot caused by a change in composition or the like of sputtering sources caused by continuation of sputtering or a variation caused by the passage of time such as a variation of lots is attempted to be reduced as largely as possible such that aging is monitored in manufacturing the recording layers, and the information is fed back for manufacturing conditions and state selection.
However, for example, a variation of disks, e.g., a variation of recording power sensitivities in the inner and outer peripheries or the like cannot be attempted to be sufficiently reduced in the manufacturing processes. For this reason, under the present circumstances, a variation caused by manufacturing cannot be easily suppressed within a small margin.
Therefore, in manufacturing an optical recording medium with a conventional configuration, when a finally obtained optical recording medium falls without a correction range obtained by information written in the premastered area, a method for wasting the optical recording medium and remanufacturing a optical recording medium is employed.
However, in such a method, as described above, when a margin is narrowed with an increase in density, the amount of waste increases. Therefore, due to a decrease in yield and a high cost, but also concerns about saving resources, environmental problems, energy saving, or the like, waste or remanufacturing is posed as a serious problem.
The present invention is to provide an optical recording medium, an optical recording method, an optical reproducing method, and an optical recording/reproducing device which attempt to solve these problems, i.e., which can increase a yield and which can stably perform optical recording and optical reproducing under optimum conditions.
More specifically, an optical recording medium according to the present invention has a writable recording layer on a substrate and has a maker recording area on which a maker performs recording on the recording layer, and individual drive control information of the optical recording medium is recorded in the maker recording area.
More specifically, in the present invention, not only a serial number or a normal maker code, but also optimum drive control information are recorded in the maker recording area.
The drive control information is an individual variation in optical recording media, for example, all or part of respective information on a recording sensitivity, a reproducing sensitivity, temperature dependency of a recording sensitivity, temperature dependency of a reproducing sensitivity, linear speed dependency of a recording sensitivity, linear speed dependency of a reproducing sensitivity, recording magnetic field sensitivity, reproducing magnetic field sensitivity, an optimum resolution, optimum asymmetry a change in sensitivity caused by repetitive recording, and a change in sensitivity caused by repetitive reproducing.
According to the present invention, in an optical recording method for an optical recording medium having a writable recording layer on a substrate and having a maker recording area and a user recording area formed on the recording layer, individual drive control information of the optical recording medium is recorded in the maker recording area, and the optical recording method comprises the steps of controlling a drive circuit based on the drive control information and performing optical recording in the user area by the drive circuit.
According to the present invention, in an optical reproducing method for an optical recording medium having a writable recording layer on a substrate and having a maker recording area and a user recording area formed on the recording layer, individual drive control information of the optical recording medium is recorded in the maker recording area, and the optical reproducing method comprises the steps of controlling a drive circuit on the basis of the drive control information and performing optical reproducing from the user area by the drive circuit.
In addition, according to the present invention, an optical recording/reproducing device for an optical recording medium having, on a substrate, a premastered recording area written by a pattern obtained by molding when the substrate is molded, and having a writable recording layer on the substrate, a maker recording area and a user recording area being formed on the recording layer, using an optical recording medium in which individual drive control information of the optical recording medium is recorded in the maker recording area, includes a recording/reproducing laser, an automatic power control circuit of the laser, an emission power monitor for the laser, a premastered signal detection unit for detecting a premastered signal in the premastered area of the optical recording medium, a maker signal detection signal for detecting a maker recording signal of the maker recording area, a temperature sensor, a control circuit, and an error detection unit, and a memory.
By the control circuit, the error detection unit, and the memory, on the basis of error-free signals of the premastered signal and the maker recording signal, a correction value to a standard value is obtained, a control signal subjected to temperature correction on the basis of temperature information obtained from the temperature sensor is obtained, the control signal and a monitor signal obtained by the emission power monitor of the laser are guided to the automatic power control circuit, and optical recording and optical reproducing to the optical recording medium are performed while the emission power of the laser is automatically controlled by the automatic power control circuit.
As described above, according to the present invention, not only information recorded based on a standard value serving as, e.g., a design center, determined when the substrate of the optical recording medium is molded, i.e., but also the individual information of the optical recording medium, i.e., information based on a variation of optical recording media are recorded in the maker recording area, so that optical recording and optical reproducing can be performed on the basis of the information. For this reason, when the respective optical recording media are shifted from the standard value recorded in the premastered by a regulation or more, on the basis of the information recorded in the maker recording area, excellent optical recording or reproducing can be performed.
Incidentally, in a conventional optical recording medium, in a recording area only for a maker, only a maker code, a serial number, and the like are described, and any recording related to drive control information in recording and reproducing is not performed.